Pressure switch



A. C. SMITH PRESSURE SWITCH July 21, 1931.

Filed April 30. 3,950

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Patented July 21, @3l

.ARTHUR C. SMITH, F ALLEYTON, TEXAS, ASSGNOR 0F ONE-HALF TG L.. T. EVERETT, OF ALLEYTON, TFAS FEFSS'UEE Sl/VITCH Application filed April 30,

The present invention relates to improvements in the construction and operation of pressure indicators for .pneumatic tires and the like.

lt is a well recognized fact that the life and wearing qualities of pneumatic tires are materially prolonged, if the tires are maintained at a proper and even pressure.

llt is, therefore, a primary object of the present invention to provide simple, efficient and economical means for indicating to the driver when the pressure in any of the tires exceeds or falls below a predetermined limit.

A further object c omprehends the provision of means responsive to variations in the pressure of each of the tires for closing an electric circuit, so as to operate an audible or visual signaling device or both simultaneously.

Another object of the invention consists in operatively associating movable contact iin igers with a stationary contact whereby the 'ngers are selectively or alternately moved into engagement with the fixed Contact to close an electric circuit when the pressure in the tire becomes too great due to overexpansion by heat or other causes, or when thc pressure falls below the proper pressure that should be maintained.

Further objects and advantages of the inn vention will become apparent from the following description, when taken in conjunction with the accompanying claims and drawings.

Referring to the drawings in which is shown a preferred embodiment,

Figure 1 is a fragmentary view, with parts in section, of a vehicle wheel showing the indicator associated therewith.

`Figure 2 is a section view taken substantially along the line 2-2 of Figure 1.

Figure 3 is a sectional view taken substantially along the line 3-3 of Figure 2.

Figure 4 is a diagrammatic View showing the electrical connection of the signaling device with each of the wheels of a motor vehicle, and p Figure 5 is a detail view of the xed contact.

Referring to the drawings in which like 1930. Serial No. 448,631.

numerals designate like parts in the several views, and more particularly Figures 4f, 10,11, 12and 13 represent the front and rear wheels of a motor vehicle, each of the wheels having mounted thereon a pneumatic tire 14, the

inner tube 15 of which has its threaded valve stem 1G extending through the rim 17 and felly 18.

ln order that the driver may be immediately informed when the pressure in any of the tires exceeds or falls below the normal pressure which should be maintained, there is provided a pressure indicator having a housing 19, preferably composed of the sections 20, 21 and 22 (Fig. 1) that are con`= nected together by the bolts 23, which extend through the opposed flange portions 2A: of each of the sections. Manifest-ly, the housing 19 may be made integral, but for practical purposes, it has been found desirable to make it in sections in the manner as shown. The housing 19 is arranged to be carried by the wheel and is preferably mounted on the brake drum 25 through the instrumentality of the depending arms 26, which are clamped 'to the drum by the bolts 27 and nuts 28.

The elbow portion or section 22 of the housing` may be conveniently attached to the valve stem of the tire, so as to be readily installed on any type of wheel and has its free end terminating in an annual flange 28, which co-acts with a complementary flange 29 on the coupling` nut 30 for detachably se curing the indicator to the valve stem 16. ln order to insure a tight joint being formed between the parts a packing 31 is preferably positioned between the flange 28 and the adjacent face of the valve stem 16. The section 22 has extending laterally therefrom a tubular portion or arm 32, in which-is mount-- ed a self-seating valve that ordinarily is positioned within the valve stem 16, for controlling the supply of air to the tube 15. The outer end of the arm 32 is normally closed by the cap 33.

Mounted within the section 21 of the housing is a flexible thimble or cup 34, preferably of rubber, which is formed with an annular flange 35 arranged to be interposed between the iianges 24 and clamped in posiner tion by the bolts 23 that secure the sections together.

The thimble 3d is directly exposed to the pressure of the air in the tube and the section 22 of the housing, consequently its axial expansion will be responsive to the variation of 'the pressure in the tube 15. ilssociated With the thimble 34e and slidably mounted in the section 2O is ay reciprocating piston 36, which is connected to a rod 37 that extends into the elongated section 2O of the housing (Fig. 2). A coil spring 38 is confined between the piston 36 and the flange portion 39 et the section 21, so as to exert a pressure sutlicient to counter-act the normal air pressure in the tire 14, which pressure tends to maintain the nipple 3d distended to its normal position as shown in `figure 2. Positioned Within the section 2O ot the housing and transversely disposed relative to the piston rod 37 is an operating lever l0, Which is provided with a central slot 4:1 and the end slots 4t2, and is pivotally connected to the housing as at i3 at a point between 'the central slot 41 and one et the end slots 42 for a purpose which viill be subsequently described. The tree end of the piston rod 37 is connected as at le 'to the central slot lll, 'While the movable contact lingers l5 and i6 are pivotally secured in each oi the slots 42 by the pins if? in the manner as shown in Figure 3. The inner end of each of the contact fingers Ll5 and d6 is sliclably mountedin the recessed portion i8 of the section 20, While their outer ends lll extend a limited distance beyond the hous ing', so as to be moved by 'the actuation ot 'the rod 3'? into engagement with a Alived annular contact member 50, that is ca ied by the stationary portion 51 of the bralre drum or vehicle andseparated therefrom by strip of any suitable insulated material such as 52. yl`he fixed contact is electrically conn nec'ted by Athe wire 53 to any suitable signaling device, such as the lights 54, 55, 56V and 57, that may be mounted on the dash of the vehicle, so as to be positioned convenient to the driver. Additionally, an audible signal such a horn or the like 58 may be inserted in the circuit, so that when the switch is turned on and either ot the movable contacts Ll5 or i6 is moved into engagement with the lined contact 50, a circuit is established 'which simultaneously turns on one ot the lights and sounds the horn. The fixed con- 56 may be carried in an annular oll'set portion 59 1) formed in the stationary support 51` and is detachably connected thereto by al series of peripherally spaced bolts 60 and nuts 61 (Fig. 5). As the heads of the bolts 60 are flush With the exposed face of the tixed contact or run ring 50, the 'wire 53 is preferably connected to one et the bolts 60, so as to establish a closed circuit when either of the movable contacts are brought into engagement with the fixed conn tact.

Referring to Figure [l of the drawings9 it ivill be seen that each ot the Wheels of the vehicle is provided with a pressure indicator 19, which, 'when either o'lf the lingers /15 or i6 is moved into engagement with the lined contact 50, closes an electric circuit that lights one ot the bulbs 54:, 55, 56 and 57 on the dash and also operates the hcrn 58. 'llhe movable contacts 45 and 46 may be grounded on the metallic part of the drum as indicated by the numeral 63, While a battery 6l carried by the vehicle may be connected to the circuit adjacent the horn 58 by the wire 65 and is grounded as at 66, so as to provide a closed circuit when the pressure in any oi the 'tires exceeds or falls below the proper pressure 'that should be maintained.

operation, the spring 38 is tirst adjusted to eiert suliicient pressure to counteract the normal air pressure in the tire which tends to maintain the nipple 34rin its distended position, so that this piston 36 and its associated parts are relatively stationary. Should the pressure in the tire 1d tall below normal, the nipple 3l Will be contracted by the increased pre. sure et the spring 38, thus causing the piston 36 to move outwardly or to the left as shown in Figure 2, which, in turn actuates the lever d0, so as to cause the latter to nieve about its pivot or iulcruin and bring the linger 4L-5 into engagement with the ixed contact 50, thus closing the circuit and causing one of the lights to be lit and the horn 'to sound. @n the other hand, should the pres sure in the tire lilbecome excessive or too great, due to overexpansion by heat or other causes it will cause the nip ale 3d to be distended beyond its normal position, which, in.

turn, overcomes the pressure oit the spring 38, thus 'forcing the piston 36 and its rod 3l' inwardly, so as to cause the contact i6 to be moved into engage.. with the lined contact 50, thus closing the circuit in substantiaily theA same manner as is ail'ected by the contact The electrical circuit et the pressure ii dica'tor is preferably connected to the other clectrieal system of the motor vehicle, so 'that it is necessary for the ignition switch to be turned on before the indicator becomes operative. lllhile both audible and visual signal devices are shown, it is quite obvious that only one of these signals may be employedn is one ot the indicators is mounted on each ot the Wheels and constitutes a separate electric circuit When the contact members carried thereby are moved into engagement with the tilted contact, it will be seen that each of the bulbs 54, 55, 56 and 57 on the dash may indicate one of the Wheels, so that when any one oij these circuits is closed, it will notify the driver what particular tire is either over-initiated or deiated.

Larnaca lt will be observed that the pressure indicator may readily be installed on all types and sizes of vehicle wheels and in cases where the wheels are not formed with brake drums the A invention and the scope of the appended claims.

`What l claim is:

l. A. fluid pressure switch for pneumatic tires comprising a movable member, means normally maintaining said member in a relatively fixed position, an operating lever pivotally connected to said member, contact fingers movably connected to said lever on opposite sides thereof, a fixed contact electrically connected to a signaling device, and

, means operable by the variation in pressure in the tire for moving one of the contact fingers into engagement with said fixed contact to close the circuit and actuate the signalin device.

2.. fluid pressure switch for pneumatic tires comprising a movable member, means normally maintaining said member in a relatively fixed position, an operating lever medially connected to one end of said member, contact lingers loosely connected to said lever and movable relative thereto, a guide means for controlling the movement of said fingers, fixed contact electrically connected to a signaling device, and means operable by the variation in pressure in the tire for moving one of the contact fingers into engagement with said fixed contact to close the circuit and actuate thesignaling device.

3. A fluid pressure switch for pneumatic tires comprising a movable horizontal member, yieldable means normally mantaining said member in a relatively fixed position, an operating lever transversely disposed relative to said member and pivotally connected thereto, contact fingers loosely connected to said lever and extending'outwardly therefrom, a fixed contact electrically connected to a signaling device, and means operable by said movable member and arranged to engage said fixed contact to close the circuit when the pressure in the tire exceeds or falls below a predetermined limit.

4. ln a fluid pressure switch for pneumatic tires, a housing, a reciprocating piston mounted in the housing, means for normally maintaining said piston in a relatively fixed position, a lever connected to said piston and pvoted intermediate its ends to said housof a preferred-embodi- Y nicating with lnga from said housing and operatively connected to said lever, a fixed contact electrically connected to a signaling device and arranged to be engaged by said fingers for closing an electric circuit, and means when the pressure in the tire exceeds orlfalls below a predetermined limit for actuating said piston to move one of the fingers into engagement with the fixed contacts to close the circuit and actuate the signaling device.

5. ln a fluid pressure switch for pneumatic tires, a housing, a reciprocating rod mounted in the housing, a flexible member responsive to the pressure change in the tire for actuating said rod, yieldable means for normally maintaining said rod stationary, a lever loosely connected to one end of said rod, means pivotally connecting the lever to the housing, contact fingers operatively connected to said lever, and a fixed contact electrically connected to a signaling device and arranged to be engaged by said contact ngers.

6. A Huid pressure switch for pneumatic tires comprising a housing directly commuthe valve stem of the tire, a reciprocating rod mounted in said housing, a horizontally disposed flexible member responsive to the pressure in the tire for actuating said rod, yieldable means for normally maintaining said rod stationary, a horizontal lever transversely disposed relative to said rod and loosely connected medially to one end of the rod, means pivotally connecting said lever to the housing at a point between its connection to the rod and one end thereof, contact fingers loosely connected to said lever on opposite sides of said rod, and a fixed contact electrically connected to a signal device.

7. A fluid pressure switch for pneumatic tires comprising a housing directly communicating with the valve stem of the tire, a reciprocating rod mounted in said housing, a horizontally disposed flexible member responsive to the pressure in the tire for actuating said rod, yieldable means for normal- -ly `ina.intaining said rod stationary, a horizontal lever transversely disposed relative to said rod, and provided with a series of longitudinally disposed slots, means loosely connecting said rod to one of the slots, means pivotally connecting said lever to thel housing at a point between its connection to the rod and one end thereof, contact fingers normally extending parallel to said rod and on opposite sides thereof, means loosely connecting said contact fingers to complementary slots in. said lever, and a fixed contact electrically connected to a signal device.

ln testimony whereof l have hereunto set my hand.

v ARTHUR C. SMTH.

contact fingers i extending outwardly lll@ 

